Mass flow controllers (MFCs) having a quick-response (also known as fast-response) mode are currently used in many applications in the semiconductor and other industries. Applications in these industries not only require MFC modes that operate quickly, but the applications also require that the MFCs limit overshoot of a desired mass flow rate. Furthermore, MFC quick-response modes need to provide consistent responses across varying flow conditions throughout various steps of the MFC process. For example, it would be beneficial in certain applications that MFCs produce quick and accurate flow rates across varying pressures for various setpoints and across multiple gases for multi-gas applications.
Most mass flow controllers are currently calibrated at the manufacturer using N2 gas. Therefore, MFC performance is currently guaranteed only for N2, and MFC performance may significantly degrade when the MFC is used with other gases. Calibrating MFCs with each specific operating gas is not possible due to the high cost of doing so. Furthermore, it may not be possible to calibrate a MFC for many gases due to the gas properties. For example, some gases may be toxic or highly flammable. Also, calibrating a MFC with a “surrogate” gas having properties similar to the operating gas properties, but without the unwanted gas properties may not be possible or effective for many gas types.